Earth’s
AtmosphereThe composition
of Earth’s earliest atmosphere remains unclear and is a subject
of active investigation by geologists. Some geologists believe that
the earliest atmosphere included large amounts of nitrogen. Others
believe that it was composed largely of carbon dioxide and water vapor,
along with some other volcanic gases. These gases would have come
from steaming vents and volcanoes that were common across the Earth’s
surface. Early in the Hadean, Earth’s atmosphere was probably
too hot to allow liquid water to condense, but fragments contained
within younger rocks suggest that sedimentary rocks formed later in
the Hadean, which implies the existence of surface water.